Commonly assigned U.S. patent application Ser. No. 08/899,042, filed Jul. 23, 1997, xe2x80x9cTape Pre-formatting with Uniform Data Storage Segments Selectively Mapped to Fixed or Variable Sized Independently Addressable Data Storage Partitionsxe2x80x9d, Basham et al., is incorporated for its showing of a data storage drive and method for formatting data storage cartridges to various capacities, called flexible capacity scaling.
Commonly assigned U.S. Pat. No. 5,546,557, xe2x80x9cSystem for Storing and Managing Plural Logical Volumes in Each of Several Physical Volumes Including Automatically Creating Logical Volumes in Peripheral Data Storage Subsystemxe2x80x9d, Allen et al., is incorporated for its showing of a system for storing and managing plural logical volumes in each of several physical media volumes in an automated data storage library.
This invention relates to automated data storage libraries for storing and retrieving data storage media, and, more particularly, to the capacity scaling of such media and to the attributes of the library components.
Automated data storage libraries are known for providing cost effective access to large quantities of stored data. In an automated data storage library, numerous storage slots, or cells, are arrayed within the library and are used to hold data storage media, such as magnetic tape cartridges or cassettes. (The term xe2x80x9cmediaxe2x80x9d used herein refers to any portable housing structure containing any type of data storage media.)
In a conventional automated data storage library, the storage slots are arranged in a planar or cylindrical orthogonal arrangement of rows and columns, forming a xe2x80x9cwallxe2x80x9d of storage slots for holding data storage media. An accessor, furnished with one or more pickers, is a robotic device which moves along a guideway in a horizontal motion, or about a pivot in a rotary motion, and moves vertically to access the various storage slots with the picker, and transports selected data storage media amongst the storage slots and one or more drive units, which read and/or write data on the data storage media. To double the storage capacity, two xe2x80x9cwallsxe2x80x9d of storage slots may be provided on either side of the accessor.
Libraries also typically contain input/output stations or ports through which an operator may pass data storage media to be added to the library and through which the accessor may pass data storage media to be removed from the library.
The operation of the accessor is typically under the direct control of a library manager, which is a programmed data processing controller typically situated in the library. A library manager typically comprises a micro-processor, including a database such as memory or a disk drive, and input/output adapters, such as SCSI ports. The disk drive typically stores the programs (microcode) which cause the manager to operate the library, and which include information indicating the characteristics of the particular library. The programs for the library manager may be installed or updated by a typical input device, such as a CD-ROM optical drive. The library manager is interconnected with one or more host computer systems, such as a mainframe or network computer, which issues commands to the library. The library may conventionally be arranged to retrieve and store data for a variety of hosts, often connected to the library over the same network. The host typically commands the library to retrieve a selected data storage media and deliver the data storage media to a data storage drive of the library.
The drive units may be directly interconnected with the host(s) over host/drive interfaces and, after a data storage media is delivered to a drive unit, it typically searches for, and reads selected data from or writes data to the selected data storage media in response to commands from the host. Each drive unit typically includes a drive and a controller for operating the drive. One example of a drive unit arrangement employing a single controller for operating a plurality of magnetic tape cartridge drives is the IBM 3590 Model A50 Data Storage Subsystem.
A number of different companies manufacture automated data storage libraries today, each model displaying various different features. One example is the IBM 3494 Data Storage Library, which stores magnetic tape cartridges, and employs IBM 3590 Data Storage Drives.
The incorporated Basham et al. U.S. patent application describes a method for formatting data storage cartridges to various capacities, called flexible capacity scaling, as employed, for example, with an IBM 3590 Data Storage Drive and IBM 3590 magnetic tape data storage media. Basham et al. describes the tape as a multi-track linear data storage media, which may have data blocks recorded in bi-directional serpentine patterns. Fixed capacity scaling, rather than storing the data blocks on several tracks or track groups sweeping the entire length of the tape, is the congregation of the data on all tracks of the tape near the beginning of the tape. Flexible capacity scaling stores the data blocks on a multi-track tape using a hybrid serpentine pattern, comprising separate sets of serpentine patterns along the length of the tape. Flexible capacity scaling is defined as the arrangement of the data blocks in a continuous configuration of multiple adjacent stacked serpentine patterns. The configuration is continuous in that sequential access to all data blocks is possible without advancing the tape to skip over any regions intervening between adjacent ones of the ordered data blocks.
As described in Basham et al., the fixed capacity scaling or the flexible capacity scaling of a tape is accomplished by the drive controller operating the drive to pre-format a tape, and is invisible to the host. By congregating the data blocks near the beginning of tape, tape head movement is advantageously restricted to only part of the tape and time consuming tape advancement operations are avoided in favor of small, relatively rapid operations to xe2x80x9cverticallyxe2x80x9d align the tape head and data path and then indexing the tape head or switching to a different tape head.
In order to implement the above tape pre-formatting, the host must be programmed to command the drive to conduct preformatting of the tape.
Automated data storage libraries, however, as described above, operate with a variety of host processors, some of which may have different operating systems-and application programs. For example, host processors may comprise an IBM personal computer, IBM model RISK System/6000 computer, IBM model AS/400 Advanced Systems computer, Sun workstation, HP workstation, IBM 3090 mainframe computer, or other suitable data processing apparatus. Thus, each of the different hosts may have to be provided with a special program in order to be enabled to command the drive to conduct pre-formatting of the tape.
Further, ones of the variety of hosts may have programming to communicate with data storage drives having differing interfaces, such as an IBM 3490-type of interface, an IBM 3490X-type of interface, an IBM 3590-type of interface, or an IBM 3590X-type of interface. The drive controller for the data storage drive of the IBM 3590 Model A50 Data Storage Subsystem has the capability to communicate in the protocol of ones of such a plurality of interfaces, and may be switched in an initialization process. However, in an automated data storage library, it may not be possible to dedicate a data storage drive to a single host.
It is an object of the present invention to allow capacity scaling of data storage media stored in an automated data storage library.
It is another object of the present invention to allow host/drive communication by data storage drives in an automated data storage library with differing interfaces.
Disclosed is an automated data storage library for storing and retrieving data storage media in a plurality of storage slots, for a host processor, the host processor signaling the automated data storage library to retrieve a selected data storage media. At least one drive unit is coupled to the host processor for reading and/or writing data on the data storage media, and at least one robotic accessor transports the data storage media between the storage slots and the at least one drive unit. A library manager is coupled to the host processor, to the at least one drive unit and to the at least one robotic accessor. The library manager includes a stored table for identifying the data storage media stored in the storage slots, the stored table indicating artificial scaling the data storage capacity of selected data storage media to selected values less than the actual data storage capacity thereof. The library manager responds to the retrieve signal from the host processor, signaling an accessor to transport the selected data storage media to a drive unit, and signaling the drive unit to artificially scale the data storage capacity of the selected the data storage media to the selected value therefor identified in the stored table. In accordance with a more specific aspect of the present invention, the library manager signals the drive unit to detect the presence of the artificially scaled data storage capacity format at the selected data storage media, and if the artificially scaled data storage capacity format is absent, to format the selected data storage media to the artificially scaled data storage capacity.
In accordance with another aspect of the present invention, the library manager of the automated data storage library is coupled to the host and receives commands from the host designating certain ones of the data storage media as having the artificially scaled capacity. The library manager responds thereto by providing the artificial scaling indicator for the designated ones of the data storage media in the stored table.
In accordance with still another aspect of the present invention, at least one drive unit of the automated data storage library is coupled to a host at a drive/host interface for reading and/or writing data on the data storage media. The library manager is coupled to the at least one host, coupled to the at least one drive unit, coupled to the at least one robotic accessor, and has a stored table. The library manager stores, in the stored table, indicators of attributes of the automated data storage library with respect to ones of the data storage media. In response to the retrieve signal from the host, the library manager signals the accessor to transport the selected data storage media to a drive unit, and signals the drive unit to operate in accordance with the attributes from the stored table for the selected data storage media, such as signaling the drive unit to communicate at the drive/host interface in the protocol of the attributes indicated for the selected data storage media in the stored table.
For a fuller understanding of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings.